Machines for applying closures to containers are well known and widely used. The present invention relates to the application of threaded closures to containers having threaded necks, and is particularly directed to the application of closures to containers which hold consumable liquids, such a milk.
It is nearly impossible with practical cleaning systems to remove all milk residues and deposits from the milk contact surfaces of milk bottling and capping equipment. One of the major difficulties with most currently used equipment, closures and containers, is the need to thoroughly and frequently clean the equipment so that the contents of the containers is not contaminated.
Overtightening or stripping of the threaded connection between the closure and the container is also a problem. Applying threaded closures to milk containers is particularly problematic because milk is lubricious, making stripping a significant problem in milk bottling operations.
Many bottlers, for convenience and to reduce costs associated with shipment of empty containers, blow mold containers on-site. Because many bottlers do not have expertise in blow molding operations and, in particular, tooling maintenance, serious problems can arise, such as bottles being molded to configurations which significantly vary over time. In some instances, bottlers have other difficulties maintaining consistent quality in the manufacture of their bottles. Problems such as excessive flash, mismatching of mold components, excessive parison pleating, and non-round openings are common in on-site blow molding operations. While caps are generally molded to relatively precise and consistent dimensions, blow molded bottles generally are not, particularly bottles made by bottlers who blow mold bottles on-site. To provide a reliable closure on bottles of varying dimensions and quality is a difficult challenge for cap suppliers.
The present inventions have particularly beneficial application in turret-type capping equipment of the general type shown and described in the following U.S. Pat. Nos. 3,771,284; 5,197,258; and 5,473,855. However, the spindle assembly and related rotation inducing equipment could be used in other types of machinery. When used with turret-type machinery, a cap feeder assembly is used to bring a cap into initial proximity to a moving container neck. A conveyer brings the container into engagement with the cap and delivers the container (with the cap loosely disposed atop the container) to a capping station on the turret. The container support of the turret holds the container in vertical alignment with a spindle assembly. When the container support engages a cam, the container (with a cap loosely positioned on the container neck) is lifted into engagement with a chuck at the lower end of a drive shaft of the spindle assembly. The drive shaft of the spindle assembly has a chuck carried by the lower portion of the spindle, which grips the cap as the bottle and cap are brought into engagement with the chuck.
When the turret rotates, a pinion gear at or near the upper end of the drive shaft of the spindle assembly delivers torque to the drive shaft due of the engagement of the pinion gear with a stationary and much larger gear wheel mounted atop the turret. In a typical turret capping machine the gear wheel is continuous. However, as shown in U.S. Pat. No. 5,473,855, the gear wheel may be less than a full circle, and torque may be delivered to the drive shaft intermittently. The interface where torque is transferred from gripping jaws on the chuck to knurls formed on the outside surface of the cap (i.e., the chuck/cap interface) is designed to prevent stripping of the cap as it is tightened onto the threads of the container.
In one embodiment described herein, a cap is designed to have a series of areas where some of the knurls on the exterior of the skirt portion of the cap extend radially outwardly beyond other knurls, such that the extended knurls are the primary points of contact with the gripping jaws of the chuck. If the cap tightens before the spindle assembly stops rotating, the extended knurls deflect and allow continued rotation of the chuck, even though the cap has stopped rotating, thus preventing the stripping of the threads of the cap relative to the threads on the container neck.
Thus, the knurls on the cap and splines on the jaws inside the chuck as described herein are specifically designed to simplify and facilitate the application of threaded caps to threaded containers. The chuck/cap interface described and claimed herein is designed to reduce the number of moving and fixed parts by eliminating the need for a clutch mechanism in a capping spindle. This objective is achieved the a chuck and cap combination that includes a very simple and easily cleaned chuck and a cap with a specially designed surface that is contacted by the jaws of the chuck.
Furthermore, the simplicity of chuck described and claimed herein significantly reduces down time needed to clean and disinfect the capping machine and reduces the chance of unwanted bacteria from making its way into any bottles.
These and other objects and advantages of the present invention will be better understood upon a reading of the following specification read in conjunction with the accompanying drawings.